Electric switch.



PATENTED FEB. 12, 1907.

J. G. PINKERTUN. ELECTRIC SWITCH. APPLICATION IILBD MAY 9, 1906.

nor, in the UNITED STATE$MPATENT OFFICE.

Specification of Letters Patent.

Patented Feb. 19, 1907.

Application filed May 9, 1906. Serial No. 315,961.

To all lU/MNTL it may concern/.-

Be it known that 1, JAMES C. PINKERTON, a citizen of the United States,residing in Philadelphia, Pennsylvania, have invented certainimprovements in Electric Switches, of which the following, is :ispecification.

(Joe object of my invention is to provide it relatively simple andsell-contained pneumatic electric switch, particularly adapted for usein connection with air-brake and stcunrcompressor plants, it beingfurther de sired that the device shall have its parts arranged in asubstantial manner and so disposed as to require but little attention orrepairs. These objects I attain as hereinafter set forth, referencebeing lied to the accompanying drawings, in which- Figure 1 is avertical section of a switch constructed according to my invention. Fig.2 is a front elevation of the piston. Fig. 3 is a vertical section ofthe piston, taken on the line b 3, Fig. 2. Fig. -l is (t side elevation,partly in section, illustrating a niodil'ir-d form of my device. Fig. 5is a. plain view of the dc- Vicc shown in Fig. l, and Fig. (5 is e.vertical section on the line (3 c, Fig. 4.

Referring to Figs. 1 to 3 of the shove drswings, A is at cylinder lowinga removable heard a, to which is connected :2. pipe e, lend ing from theair-rrserroir ol' the compressor system. Said cylinder is supported onfeet or brackets (1, and has within it a piston B, provided Willi k1piston-rod which extends through and is guided by the end ol thecylinder opposite that entered by the pipe (1/. Said piston-rod has onits projecting end a. nut 11', so placed as to limit the inward movementof the piston l3.

Confined between the piston and the end a oi the cylinder is nrelulivcly strong spring l), tending to maintain sold piston :idja-ronito the coal (L ol the cylinder. 'lhcro upon one have in material.fastened to is in any desired nunpi'esonl. inslsnce by s rews, nodprovided with to o slol s d and :1. of uhich o metallic pLilc or stripit". 'llsis latter piece is held =1. position by moon? l' it i screw (1extending through but insulated from the body of the piston B andprovided WilLlLDUtS for the iittiiclu'nent oi an-olcclricol conductor.Moreover, so id piece 11 is so supported within the slot or channel (1'that while ils upper end is PlllOl irully level with the [awe of theinsuln ting-plot e I) its lower end is some distance below said face,and similarly the inl l l l f air in iiirreserv ir suleting materielforming the bottom of the slot or channel (I is so shaped that its lowerend is substentiell T level with the face of the plate I), while itsupper end is some distance below said level As it consequence there isat each of the points cl and d, where the two slots come together at topand bottonnc. relsr lively ebru p t ed go or abutment, for c purposehereinafter noted.

A s 'iring-nrni E is held to the head a of the cylinr. or A by means ofu bolt a extending through but insulated from said heed so as to form onthe outside of the cylinder a. terminal lor the attachment of anelectrical condoctor, and said ttlill is so made that it con tinucllytends to place itself in the position shown in dotted lines in Fig. 1.It is, more over, so supported that its head e, which is rounded, asshown, enters the grooves or channels d and 15, so as so beer againstthe bottom portions illf'lOuf. Connected to the bolt d upon the piston Bis it flexible conductor 7", extending; through the head a? of thecylinder, from which it is electrically insulofted by means of i1 libwbushing ;f"', as shown.

Under opcrnting conditions the electric motor for operating thecompressor-pump has one terminal connected to the bolt (1 its secondlcriuiiml lujilig coimmltd to one of the line (Qlillll i'ifli'l*, Whilethe second line conductor is conn ccicd to the bolt *5 through therelatively flexible wire ,1.

u if the 111521 Visit of the compressor system be empty, the piston iiwill occup the position shown in Fig. i, and 51-8 3 consequence thespring-nun i l will be in contact with the lower portion of the metallicpiece d". The motor-circuit is thcrclorc complete and the motor willoperufo. so us to mun-re the sir-pump to comprcss conocciml to the pipea.

the iiu ircrv-iirc rises the piston ll is mo'vrd ill iho ryliudw'lmrzird the end it he iisl n :1. plate l), of insulating;

lh ro-l'; but ilio 1 ili'iz t 1 i" the electric unit-:11;

\ sprin in [he hi icr j -L'tllli. ll l ollou's ilu ioo'i'omout oi thepiston in such iormwr llwl ils lithtll Il'f',lit=Ll]lS in contort u ii hlll( iucoilliv strip (l When, ,limvorvr, said pislou lam; oo unwed tosuch so. cxicul l. l, )H'Ifbl 1hr sprin i oriu i l to occugrr l'hopordlintl iodi -iite-d in dotted lines in Fig.1. l, said tl-l'lil lllPV-I- h oil of the upper end oi the strip d, suddenly breathing; the notlu'-circuil. by rcosou of the loot that it drops iroiu wlmispractically llH level of the front face of the nsuIdling-piece l) to thelowermost portion of the slot or channel (1.

As a con equence the operation of the motor is stopped, and no furthercompression of air takes place in the reservoir. As the compressed airis gradually used from said reservoir and its pressure drops thespring 1) acts to foree the piston B toward the head a of the cylinder,thereby causing the end of the s ring-arm E to move downwardly throughtlie channeLd, which being bounded wholly by insulating materialprevents passage of current to the n'iotor-circuit. When, however, thepiston B has moved to approxim'at'ly the position shown in Fig. l, thehead 2 of said spring-arm drops oil' the elevated lower end of thebottom or floor of the channel d to the lowermost portion of themetallic piece (1 thereby again completing the pump-motor circuit. Saidmotor then starts and compresses air, so as to repeat the above cycle ofoperations.

If desired, I may attain the same end as that above noted by means ofthe combination shown in Figs. 4, 5, and 6, in which the rod attached tothe piston has a portion 1 which atall times extends outside of thecylinder fo'r a considerable distance. This rod is provided with atransverse slot having an insulated bushing, through which extends alongitudinally-movable bar If, having brushes or contacts I) at itsrespective ends. In this form of my invention the cylinder A is providedwith a supporting-base A, ext'nded at one end and having a standard a inwhich the rod b is guided, there being held between said standard andthercar end of the cylinder 2. block G, of insulating mate rial. Thisblock has extending along each side of its upper surface metallic stripsg and each provided with a terminal g and so gilace'd as to berespectively engaged by the contacts I), carried by the arm b Said armin addition to said contacts is provided with a pin 11, designed tooperate in a groove or channel (1 formed in the up ier surface of theblock G for the reception oi its lower end. The barb is longitudinallymovable through the iston-rod b", so as to permit of its b'rus es orcontacts I) being moved into or out of engagement with the twocontactstrips g and g, which under operating conditions. arerespectively cdnnected to one terminal of the pump-motor and to theline. With. such an arrangement of apparatus and connections the channeld" is designed to maintain the contacts I) of the bar I) in engag'enientwith the two stri s g and g as the 'iston-rod 6" moves out of t ecylinder-that is, when the p'ump-motor is operating to compress air inthereservoir. As soon as thea'ir reaches suelrji pressure that thepiston approaches a predetermined oint in the cylinder A it wil be seenrrorn' ig. 5 that jt e pin b will -be guided by the channel '11" towardthe vpiston-rod b, and as ayeon'sequenqe the ar 1;, is movedlongitudinally through said rod. The contacts of said bar areconsequently moved out of engagement with the two strips 9 and 9, thusbreaking the pumpenotor circuit. Under the action of the spring 0' thepiston B is, as before, forced toward the forward end of the cylinder asthe air is used, and the pin 1) now travels in the part d of the slot (1thus maintaining the contacts b out of engagement with the strips 9 andg until the piston approaches quite near the end of its stroke. Saidchannel is then curved so as to slide the bar If through the red I)" andbring the con tacts 1) into engageincntwith the strips g and g, therebyagain starting thepump-motor by reason of the fact that the electriccircuit between the two terminals g is completed through said contactsand the bar N.

I claim- 1. The combination of a cylinder, a piston movable therein, apair of switch-contacts having terminals, means for moving the piston inthe cylinder, one of said contacts being movable relatively to the otherand being provided with means including a channel and a piece fittingtherein whereby said contact is moved into or out of engagement with theother contact as the piston is moved in the cylinder,substantially asdescribed.

2. The" combination of a cylinder, a piston therein, a spring actingbetween one face of the piston and one end of the cylinder, saidcylinder being connected to a source of fluid under pressure and therebeing a groove in the face of the piston provided with a metalliccontact-piece, a spring-actuated piece, terminals for said piece and forthe contact carried by the piston, said grooves being formed to permitthe spring-actuated piece to engage the metallic piece carried on thepiston only when said piston is moving in one direction, substantiallyas described.

3. The combination of a cylinder, a piston movable therein and providedwith a plate of insulating material held to one face, a spring actingbetween one head of the cylinder and the piston, a connection betweenthe cylinder and a source of fluid under pressure, insulating materialcarried by the piston and having a groove formed in it, a metallic striplaced in a portion of said groove, a terminal or the attachment of anelectric conductor connected to said strip, a spring-pressed arm havinga second terminal and provided with a portion operative in the groove,said groove 1 being formed to guide said springressed arm intoengagement with the metal to strip only when the piston ismoved in onedirection, substantially as described.

4. The combination of a cylinder, a iston movable therein, there being aplate 0 insulating material carried by the piston and haver, a metallicstrip 'in one 0 said parts of "the groove having a terminal for-theattachinia groove made in two parts 'oined'to each 0!;

ment of an electric conductor, a spring-aetw ated contact-pieeesupported by the cylinder so as to be capable of moving in one part ofthe groove as the piston moves in one direc- 5 tion and in the otherpart thereof, as the pislmoves in the opposite direction, and at'fminakfor said. contact-piece, substantially as described.

In testimony whereof I have signedmy name to this specification in thepresence of 10 two su bseribing witnesses.

JAMES C. PINKERTON. Witnesses I. N. DU COMB, JAB. MoGmN.

